Rapid screening of unprecedented sesquiterpenes with distinctive ring skeletons from Daphne aurantiaca employing an integrated strategy

Abstract

Guaiane-type sesquiterpenoids are well-known in medicinal chemistry of natural products, but the unprecedented sesquiterpenoid scaffold furnished by unexpected carbon–carbon linkage formation or cleavage deserves to be further explored. Herein, we report on targeted isolation of such compounds from Daphne aurantiaca, daphaulides A, B, and D (1, 2, and 4), by our integrated strategy: the Block and Grid strategy (BAGs) followed by activity screening and structure evaluation. Their structures were elucidated by NMR spectroscopic analysis, computer-assisted structure elucidation methods, quantum chemical calculations, and X-ray diffraction. The plausible biosynthetic pathways for compounds 1–5 were proposed. Compounds 2 and 3 exhibited dose-dependent inhibitory effects against cholinesterase in vitro and in silico. The experimental and theoretical results indicated that compound 3 opens up new possibilities for developing anti-cerebral ischemia agents.